Method and apparatus for feeding abrasives



Dec. 29, 1964 OLIVIERI 3,162,986

METHOD AND APPARATUS FOR FEEDING ABRASIVES Filed Jan. 18, 1963 2Sheets-Sheet 1 INVENTOR. LUIGI 0L| VIERI A TTOR EYS Dec. 29, 1964 IOLlVlERl 3, 62,98

METHOD, AND APPARATUS FOR FEEDING ABRASIVES Filed Jan. 18, 1963 2Sheets-Sheet 2 INVENTOR. LUIGI OLIVIERI ATTOR EYS United States Patent3,162,986 METHGD AND APPARATUS FOR FEEDING AREAS-IVES Luigi Oiivieri,Pisa, Itaiy, assignor to Compagnie de Saint- Gobain, Neuiiiy-sur-Seine,1 rance Filed Jan. '18, 1963, Ser. No. 252,374 Claims priority,appiication France Feb. 6, 1962 15 Claims. (Cl. 51-263) The presentinvention relates to feeding plate glass polishing tools with abrasivematerial. It consists of a feeding process and a device for theapplication of said process.

It is known that polishing tools are provided with a rubbing surfaceconsisting of a felt material. The abrasive composed of an aqueoussuspension of levigated Fe O to which a ferrous sulfate solution hasbeen added is supplied at the point between the glass and the feltmaterial. The levigated material and the sulfate are mixed insulficiently large tanks equipped with agitators.

Considering the small amounts of abrasive that are to appear under thefelts, the pipes carrying the abrasive would rapidly become cloggedwithout an abundant flow of this abrasive revolving in a closed circuitfrom the tank, where the suspension is being formed, and returningthereto. Small amounts of the required abrasive are tapped at each toolor at each tool set at dilferent points of the circuit.

The process according to the invention consists in that only thesuspension of levigated material is carried into a heavy discharge,closed circuit from which, at different points material is removed anddirected toward the polishing tools, while the ferrous sulfate solutionis added to the said tappings in adjustable quantities and strengths.

The application of this process results in an improvement of the qualityof the polish combined with the fact that this quality is maintained ata uniform level, and a notable reduction in the consumption of levigatedmaterial. The material thus economized may amount to 25%.

Applicants works indicate that this improvement is probably due to thefact that, since the ferrous sulfate solution is no longer subjected toextended circulation, the time required from the moment of its mixturewith the levigated abrasive material until its arrival at the polishingtools is too short to subject it to alteration.

Described below as a non-limiting example is a method for theapplication of the process according to the invention, as applied tocontinuous polishing of a strip of plate glass. It is illustrated by thefigures of the annexed drawings, representing:

FIG. 1 is a schematic view of the supply of abrasive material;

FIG. 2 is a view, on an enlarged scale, of the device for feeding thelevigated material, the ferrous sulfate and the feedwater and theirmixture to their entry into the discharge pipes to the polishing tool;and

FIG. 3 is an end view taken along line 33 of FIG. 2.

In these figures, the strip of glass to be polished is schematicallyillustrated as the numeral 1 and 2-2' schematically show two polishinginstruments of any conventional construction. The levigated abrasivematerial is prepared in tanks like those shown in 33', large enough forthe preparation of appropriate quantities, said tanks being providedwith rotary agitators 44 having arms such as 55'. The suspension of thelevigated material prepared in the tanks is discharged by pumps 66' intoa pipe system 77 and is fed back to the tanks 3-3, thus makinguninterruptedly a number of closed cycles before the tanks 3-3 areempty. The tanks are provided with draining cocks 8-8.

The dissolving of the ferrous sulfate is carried out in a tank 9provided with a rotary blade agitator 10. The solution is transferred bysiphoning into a second tank 11 comprising a separator wall 12 forkeeping impurities likely to be present in the solution away from theferrous sulfate solution forcing pump 13. Drainage cocks 8a are providedon the floor of the tanks 9 and 11. These-lution delivered into aconduit 14 flows into a series of tanks 15, 16 and 17 that are underpressure with respect to the tapping units 2-2'. The pump 13 dischargesinto the tank 15 which feeds t.e tank 16, thus avoiding swirlingmovements. Through the opening 20, the tank 17 is supplied with asolution of a given density. The levels in the tanks 16 and 17 are keptconstant by electrical means, not shown. The sulfate solution flowsthrough the pipes 21, 22 to the tapping units 22'.

A water tank 23 makes it possible to supply the tank 17 through opening29 in order to dilute the solution in that tank, and by means of thepipeline 24 the tapping points 2-2 can be furnished with additionalamounts of water.

The tapping unit is shown in detail in FIGURES 2 and 3. The levigatedabrasive material is tapped at 25, the ferrous sulfate at 26, and thewater at 27. The discharges are controlled by any conventionaladjustable tube clamping means such as Mohrs tweezers similar to thoseshown at 28 for controlling the rate of fluid flow in the tube. Thelevigated material is fed into an automatic feed regulator 29 of theopen cyclone type. It prevents thick grains, likely to be present, fromarriving on the strip of glass and, by swirling movements, like wiseprevents thickening of the suspension. The latter is delivered in largeamounts into the pipe 36 and in small amounts through pipe 311 into thecolumn 33 up to the level 11. corresponding to a desired discharge rate.The suspension flows from column 30 through the outlet 31 into thecontainer 39. The pipes 33, 34 and 36 return the excess amount of theregulator 29 through the spout 32 and 32' to the tank 3-3. The ferroussulfate tapped at 26 rises inside a column 37 to a level adjusted to beat the same elevation h. This solution flows out through an opening 38and mingles with the levigated material in the container 3%. The mixtureflows into funnels 4i) and 40 whence pipes 41 carry it to the polishinginstruments. The discharges of levigated abrasive material and ferroussulfate, which are in proportion at h, as well as their density, havebeen computed so that all that is required is to maintain the feedersfor the columns holding the P6 0, suspension and the FeSO solution,respectively, at the same level in order to have a supply of constantdensity and containing at all times the same percentage of FeSO Thefeedwater supplies two columns 42, 43 where it reaches a given leveldetermined by Mohrs tweezers.

As many apparently widely different embodiments of the present inventionmay be made without departing from the spirit and scope thereof, it isto be understood that the invention is not limited to the specificembodiments.

What is claimed is:

1. An apparatus for feeding an abrasive mixture to glass polishing toolscomprising means to maintain a predetermined amountof levigated materialin a first container,

means to maintain a predetermined amount of iron sulfate solution in asecond container, means to discharge levigated material from said firstcontainer, means to discharge the iron sulfate solution from said secondcontainer and means adjacent said polishing tool for receiving andmixing the discharge from said first and second containers and forfeeding the said mixture to the polishing tool.

2. An apparatus as defined in claim 1 comprising means to maintain apredetermined amount of water in a third w container, means to dischargeWater from said third container, and mixing said discharged Water Withsaid mixture before it is fed to the polishing tool.

3. An apparatus for feeding an abrasive mixture to a glass polishingtool comprising a tank for a supply of a suspension of iron oxide inWater, a closed pipe circuit and pump for circulating said iron oxidesuspension from and back to said tank, a tapping means in said closedpipe circuit, a first container in said tapping means, means to controlthe flow of said iron oxide suspension in said tapping means to maintaina predetermined level in said first container, a tank for holding asupply of iron sulfate solution, means for feeding the iron sulfatesolution in said tank to a second container, means to control thefeeding of said iron sulfate to maintain a predetermined level in saidsecond container, means to discharge said iron sulfate solution fromsaid second container, and means adjacent said polishing tool forreceiving and mixing the discharges from said first and secondcontainers and for feeding the said mixture to the polishing tool.

4. Apparatus as defined in claim 3 wherein the means for feeding saidfirst and second containers comprises flexible tube members and saidmeans to control said feeding comprises means to reduce the crosssectional area in said flexible tube members and thus reduce the flow ofmaterial therethrough.

5. Apparatus as defined in claim 3 comprising a supply of Water,'a thirdcontainer operatively connected to said supply of water, means tocontrol the flow in said water supply to maintain a predetermined levelin said third container, means for discharging said Water from saidthird container, and means for mixing the Water discharged from saidthird container with said mixture before it is fed to the polishingtool.

6. Apparatus as defined in claim 5 wherein the discharges from saidcontainer is constant at a predetermined rate and said containers aremaintained at said predetermined levels.

7. Apparatus as defined in claim 3 wherein said tapping means comprisesa first tube from said closed pipe circuit to a constant level agitatortank, an overflow tube at the top of said agitator, a second tube fromsaid agitator tank into said first container, and a third tube from saidfirst container.

8. Apparatus as defined in claim 7 comprising means for receiving thedischarges from the agitator overflow tube and said third tube and fordirecting said discharges into said tank'of the iron oxide.

9. An apparatus for feeding an abrasive mixture to a glass polishingtool comprising a closed pipe circuit, means to continuously circulatean iron oxide suspension in said closed pipe circuit, a tapping means insaid closed pipe circuit, a first container of the cyclone type, meansto introduce a flow of iron oxide suspension from said tapping meansinto said cyclone, means to continuously Withdraw excess iron oxidesuspension and thick grains of iron oxide from said cyclone, meansadjacent said polishing tool for receiving and mixing said iron oxidesuspension with an iron sulfate solution, means to control the feed ofsaid iron oxide suspension from said cyclone into said mixing means andmeans to control the feed of iron sulfate solution into said mixingmeans, and means for feeding said mixture to the polishing tool,

10. Apparatus as defined in claim 9 wherein the means to control thefeed either of iron oxide suspension or of iron sulfate solutioncomprise a container, means to control the feeding of either saidsuspension or said solution to maintain a predetermined level either ofsuspension or solution in said container and means to discharge eithersaid suspension or said solution into said mixing means.

11. Apparatus as defined in claim 9 comprising means for mixing acontrolled fiow of water With said mixture before it is fed to thepolishing tool.

12. Apparatus as defined in claim 9 comprising a supply of Water, acontainer operatively connected to said supply of Water, means tocontrol the flow of Water from said supply into said container tomaintain a predetermined level in said container, means for dischargingsaid Water from said container into means adjacent the polishing toolwherein it is mixed with said mixture of iron oxide suspension and ironsulfate solution before it is fed to the polishing tool.

13. The method of feeding abrasive material to glass polishing toolscomprising the steps of circulating a sus pension of levigated materialin a closed pipe circuit, removing measured amounts of levigatedmaterial from said closed circuit, mixing said measured amount oflevigated material with a predetermined amount of iron sulfate solution,and immediately feeding said mixture to said polishing tool.

14. The method of feeding abrasive material to glass polishing toolscomprising the steps of constantly maintaining a measured supply of asuspension of iron oxide in Water while at the same time constantlydischarging said iron oxide suspension at a predetermined rate,constantly maintaining a measured supply of iron sulfate solution Whileat the same time constantly discharging said iron sulfate at apredetermined rate, constantly mixing the discharges of iron oxidesuspension and said iron sulfate solution and immediately feeding saidmixture to said polishing tools.

15. An apparatus as defined in claim 3 wherein the iron sulfate solutionis fed through a siphon from said iron sulfate supply tank into a secondtank equipped with an impurity-retaining partition and with a pumpfeeding said solution into a third tank out of which said solution flowswithout whirling around into a fourth tank from which said solution isfed into said second container.

References Cited in the file of this patent UNITED STATES PATENTS1,136,328 Golightly Apr. 20, 1915 1,556,753 Brown Oct. l3, 19251,587,526 Hitchcock June 8, 1926 1,740,005 Crowley Dec. 17, 19292,069,261 Monnet Feb. 2, 1937 2,191,962 Jones Feb. 27, 1940 2,646,655Laverdisse July 28, 1953 2,780,038 laverdisse Feb. 5, 1957 2,873,563Thompson Feb. 17, 1959 3,028,711 Campbell Apr. 10, 1962

1.AN APPARATUS FOR FEEDING AN ABRASIVE MIXTURE OF GLASS POLISHING TOOLSCOMPRISING MEANS TO MAINTAIN A PREDETERMINED AMOUNT OF LEVIGATEDMATERIAL IN A FIRST CONTAINER, MEANS TO MAINTAIN A PREDETERMINED AMOUNTOF IRON SULFATE SOLUTION IN A SECOND CONTAINER, MEANS TO DISCHARGELEVIGATED MATERIAL FROM SAID FIRST CONTAINER, MEANS TO DISCHARGE THEIRON SULFATE SOLUTION FROM SAID SECOND CONTAINER AND MEANS ADJACENT SAIDPOLISHING TOOL FOR RECEIVING AND MIXING THE DISCHARGE FROM SAID FIRSTAND SECOND CONTAINERS AND FOR FEEDING THE SAID MIXTURE TO THE POLISHINGTOOL.